from __future__ import annotations
import gdsfactory as gf
from gdsfactory.component import Component
from gdsfactory.typings import ComponentSpec, CrossSectionSpec
[docs]
@gf.cell
def mmi(
inputs: int = 1,
outputs: int = 4,
width: float | None = None,
width_taper: float = 1.0,
length_taper: float = 10.0,
length_mmi: float = 5.5,
width_mmi: float = 5,
gap_input_tapers: float = 0.25,
gap_output_tapers: float = 0.25,
taper: ComponentSpec = "taper",
straight: ComponentSpec = "straight",
cross_section: CrossSectionSpec = "strip",
input_positions: list[float] | None = None,
output_positions: list[float] | None = None,
) -> Component:
r"""Mxn MultiMode Interferometer (MMI).
Args:
inputs: number of inputs.
outputs: number of outputs.
width: input and output straight width. Defaults to cross_section.
width_taper: interface between input straights and mmi region.
length_taper: into the mmi region.
length_mmi: in x direction.
width_mmi: in y direction.
gap_input_tapers: gap between input tapers from edge to edge.
gap_output_tapers: gap between output tapers from edge to edge.
taper: taper function.
straight: straight function.
cross_section: specification (CrossSection, string or dict).
input_positions: optional positions of the inputs.
output_positions: optional positions of the outputs.
.. code::
length_mmi
<------>
________
| |
__/ \__
o2 __ __ o3
\ /_ _ _ _
| | _ _ _ _| gap_output_tapers
__/ \__
o1 __ __ o4
\ /
|________|
| |
<->
length_taper
"""
c = Component()
gap_input_tapers = gf.snap.snap_to_grid(gap_input_tapers, grid_factor=2)
gap_output_tapers = gf.snap.snap_to_grid(gap_output_tapers, grid_factor=2)
w_taper = width_taper
x = gf.get_cross_section(cross_section)
xs_mmi = gf.get_cross_section(cross_section, width=width_mmi)
width = width or x.width
_taper = gf.get_component(
taper,
length=length_taper,
width1=width,
width2=w_taper,
cross_section=cross_section,
)
_ = c << gf.get_component(straight, length=length_mmi, cross_section=xs_mmi)
wg_spacing_input = gap_input_tapers + width_taper
wg_spacing_output = gap_output_tapers + width_taper
yi = -(inputs - 1) * wg_spacing_input / 2
yo = -(outputs - 1) * wg_spacing_output / 2
input_positions = input_positions or [
yi + i * wg_spacing_input for i in range(inputs)
]
output_positions = output_positions or [
yo + i * wg_spacing_output for i in range(outputs)
]
ports = [
gf.Port(
f"in_{i}",
orientation=180,
center=(0, y),
width=w_taper,
layer=x.layer,
cross_section=x,
)
for i, y in enumerate(input_positions)
]
ports += [
gf.Port(
f"out_{i}",
orientation=0,
center=(+length_mmi, y),
width=w_taper,
layer=x.layer,
cross_section=x,
)
for i, y in enumerate(output_positions)
]
for port in ports:
taper_ref = c << _taper
taper_ref.connect("o2", port, allow_width_mismatch=True)
c.add_port(name=port.name, port=taper_ref.ports["o1"])
x.add_bbox(c)
c.auto_rename_ports()
c.flatten()
return c
if __name__ == "__main__":
c = mmi(inputs=1, outputs=4)
c.show()
